1. Field of the Invention
The present invention relates to electrical motors, and in particular, to electrical motors used to generate heated currents of gaseous or liquid fluids.
2. Prior Art
Electrical motors are conventionally known wherein the motor coil windings are employed as a source of heat in addition to their ordinary function in the electrical motor, and wherein a fan is fitted on the central rotating axis of the electrical motor, thereby creating a current of warm air by blowing air over the heated motor coils. Examples of such devices include Japanese Patent Application, First Publication No. Sho-49-88142, Japanese Patent Application, First Publication No. Sho-616-35132 and WO900474.
In that these conventional devices consist essentially of a fan mounted on the shaft of a conventional motor, however, they retain the limitations of the conventional motor incorporated therein. Namely, when design changes are implement so as to increase heat generation by the motor coils, mechanical efficiency of the motor decreases correspondingly. When design changes are implemented so as to increase the mechanical output of the motor, heat generation by the motor coils decrease correspondingly. Consequently, conventional devices of this type are generally not suitable for applications wherein the generation of large volumes of air heated to a high temperature is required.
Additionally, in order to provide for a sufficiently high heat output, the heat generating coil winding elements may reach temperatures ranging from 500.degree. to 700.degree. C. Such temperatures, however, result in a shortened service life for the heat generating coil winding elements, and hence, for the electrical motor itself.
Moreover, when increased current flow through the coil windings is employed in order to enhance heat output, magnetically induced vibration of the coil windings occurs, thereby resulting in generation of objectionable levels of hum and other types of noise, as well as decreased service life for resistance elements due to rubbing of adjacent elements against one another as they vibrate.